KR101441122B1 - Process for desulphurizing olefinic gasolines, comprising at least two distinct hydrodesulphurization steps - Google Patents

Abstract

The present invention relates to a process for the hydrodesulfurization of gasoline fractions for producing gasoline with low sulfur and mercaptan content. The process comprises two or more hydrodesulfurization steps, i.e., HDS1 and HDS2, operated in parallel for two individual gasoline fractions constituting the source. The hydrogen flow rate in the hydrodesulfurization step HDS2 is such that the ratio between the hydrogen flow rate and the source flow rate to be treated is less than 80% of the flow rate used for desulfurization in the hydrodesulfurization step HDS1.

Hydrodesulfurization, olefin gasoline

Description

FIELD OF THE INVENTION [0001] The present invention relates to a process for desulfurizing olefin gasoline comprising two or more separate hydrodesulfurization steps,

1 is a gasoline hydrodesulfurization step of the present invention comprising two or more hydrodesulfurization steps operated in parallel for two individual gasoline fractions constituting a source, namely HDS1 and HDS2.

Figure 2 shows a further variant of the invention.

FIG. 3 illustrates a chain pretreatment step consisting predominantly of hydrogenating the diolefin, modifying the hard sulfur containing compound to a heavier compound, and a selective hydrodesulfurization step.

The present invention relates to a process for the production of gasoline with low sulfur and mercaptan content, comprising two or more hydrodesulfurization steps operated in parallel on two individual gasoline fractions. The process may optionally include a single hydrogen purification and recycle zone. The hydrodesulfurization step corresponds to at least one hydrodesulfurization zone. The hydrodesulfurization zone corresponds to one or more beds.

In the production of fuels for gasoline or diesel engines to meet new environmental regulations, it is in particular required to substantially reduce the sulfur content of these fuels. Environmental regulations require refineries in Europe to reduce sulfur content in gasoline and gas oil pools to less than 50 ppm in 2005 and to less than 10 ppm from 1 January 2009 .

The source to be treated is generally a gasoline oil fraction containing sulfur, such as from a coking unit, a visbreaking unit, a stream cracking or a catalytic cracking unit (FCC). Preferably, the source is comprised of a gasoline source from the catalytic cracking unit, and the distillation range thereof is in the range of 0 占 폚 to 300 占 폚, preferably 0 占 폚 to 250 占 폚. In the present specification, the term catalytic cracking gasoline is generally used, the term extending to gasoline, which may contain gasoline fractions from other conversion units, in addition to the catalytic cracking gasoline fraction.

The catalytic cracked gasoline can comprise from 30% to 50% by volume of the gasoline pool and is generally of high mono-olefin and sulfur content. However, almost 90% of the sulfur present in the reformed gasoline is due to gasoline from catalytic cracking. Thus, gasoline desulfurization, and in fact FCC gasoline, is very important in meeting current and future regulations. However, mono-olefins contained in gasoline contribute mainly to its octane number. In order to maintain the octane number of the gas by the olefin decomposition at a high level, it is necessary to limit the hydrogenation degree of the mono-olefin during the hydrodesulfurization treatment of the gasoline. Selective hydrodesulfurization processes have been developed for this purpose.

In addition, the desulfurized gasoline should also meet the requirements for corrosive power. The corrosive ability of the gasoline is substantially due to the presence of acidic sulfur-containing compounds such as mercaptans. Therefore, the desulfurized gasoline contains little mercaptan and its corrosiveness must be limited. However, it is now known that, among the units for selective hydrogenation desulfurization of olefin gasoline, H ₂ S present in the reactor can react with non-hydrogenated mono-olefins to form methacptans. The fraction of mercaptans in the resulting gasoline is generally higher as the sulfur content in gasoline is lower. In order to minimize the mercaptan content, it is generally desirable to operate at a high hydrogen flow rate. However, this increases the costs associated with compressors, recycling and hydrogen purification. In order to overcome this problem, the present invention is able to limit the energy consumption of the compressor, while at the same time providing a solution that can reduce the content of mercaptan and increase the octane number against a constant sulfur content in the desulfurized gasoline.

On the other hand, due to changes in the global automotive market, refineries are being forced to produce gas oils for diesel-engine vehicles, depending on the situation, or to study the possibility of maximizing the production flexibility and thus the production of gasoline. Thus, refiners may find it very feasible to have the lowest cost possible option to transport the heavy gasoline fraction at the disposal, as needed, to gasoline pools or middle distillate pools.

European patent application EP-A1-0 725 126 describes a process for hydrodesulfurizing catalytic cracking gasoline while limiting octane loss through mono-olefin hydrogenation. The process comprises the step of distilling gasoline into a plurality of fractions comprising one or more fractions rich in a compound that is difficult to desulfurize selected from thiophenes and alkylthiophenes and one or more fractions of thiacyclopentane, Thiophene, and alkylbenzothiophene enriched fractions. At least one of the two fractions is treated by the hydrodesulfurization process and then mixed with the untreated fraction.

The process has the disadvantage of requiring analysis of different fractions before treatment and does not describe how to select the fractions to limit the amount of mercaptan in the final desulfurization product.

U.S. Patent US-B2-6 596 157 discloses a gasoline heavy fraction, referred to as HCN (heavy cat naphtha) under non-selective hydrodesulfurization conditions, and an intermediate cat naphtha (ICN) Described is a method of desulfurizing a gasoline fraction of a gasoline middle fraction from a cracking unit, in parallel, based on said process, wherein the intermediate gasoline (ICN) is heated by a hydrogenated heavy fraction (HCN).

The patent does not describe a method of treating a variety of oils to limit the fraction of sulfur-containing compounds in the form of mercaptans in the desulfurized gasoline. In addition, according to the disclosure of the patent, the lightly solubled fraction, referred to as LCN (light cat naphtha), is generally subjected to further desulfurization treatment, for example using a solution containing sodium hydroxide to extract mercaptans Step.

Regarding the problem of extracting mercaptans from the hydrodesulfurized cracked gasoline, the current solution described in US-A-6 960 291 consists of pre-treating the hydrotreated gasoline to deplete the mercaptan. Many methods have been devised. As an example, reference may be made to WO-A-01/79391, which describes a method of reducing mercaptan content by treating partially desulfurized gasoline using various methods, such as adsorption, extraction with sodium hydroxide, have. However, this method has the disadvantage that it is necessary to use the additional step of treating the gasoline, and that there is no flexibility to transfer a particular oil to a gasoline pool or a middle distillate pool.

US-A-2003/0042175 describes a process for the desulfurization of cracked gasoline which comprises various treatment steps to reduce the sulfur content. The method comprises the steps of converting the light sulfur containing compound by a diolefin hydrogenation step, weighting, distilling the gasoline into a plurality of fractions, and desulfurizing at least a portion of the resulting heavy fraction of gasoline . However, the above patent does not disclose a method of treating the gasoline to minimize the content of mercaptan in the desulfurized gasoline, or a method of treating hydrogen from the hydrodesulfurization step.

SUMMARY OF THE INVENTION In summary, the present invention provides economically viable triple problems of reduced sulfur content in fuels, limited mercaptan content in low sulfur gasoline, and flexibility to orient fuel production with gasoline fractions or intermediate distillates, depending on market demand And presents a new solution to solve the problem. It is also important to integrate the problem of controlling energy consumption with any new ideas in the current situation where greenhouse gas emissions must be reduced. The method described in connection with the present invention is innovative as it allows for simultaneous processing of the above described triple problem while limiting energy consumption due to the required compression of hydrogen recycled to the hydrodesulfurization step. Gasoline has a research octane number (RON) and sulfur content (S) such as RON ≥ 90.70 and [S] ≤ 50 ppm, preferably RON ≥ 90.70 and [S] ≤ 37 ppm, more preferably RON ≥ 90.75 and [S]? 35 ppm, more preferably RON? 90.80 and [S]? 31 ppm. Each of the octane number and sulfur content is associated with a motor octane number (MON: motor octane number), e.g. MON ≥ 79.45, preferably MON ≥ 79.50, and more preferably MON ≥ 79.55.

The present invention is based on different treatments of the various oils constituting the gasoline fraction.

For contact cracked gasolines, the hard fractions are rich in mono-olefins and saturated sulfur-containing compounds such as mercaptans and sulfides. The term "hard segmentation" means a gasoline fraction having a boiling point of less than 100 ° C, preferably less than 80 ° C, more preferably less than 65 ° C. The heavier fraction of gasoline is rich in benzothiophene sulfur-containing compounds such as benzothiophene and alkylbenzothiophene, and to a lesser extent, alkylthiophene. In addition, the aromatic compound is rich and the olefin compound is insufficient. The heavy fraction of gasoline is composed of hydrocarbons having a boiling point of greater than 160 ° C, preferably greater than 180 ° C, more preferably greater than 207 ° C. The heavy fraction of gasoline is generally a fraction containing most of the sulfur. The heavy fraction of the gasoline may be incorporated into a gasoline pool or a middle distillation fraction to produce kerosene or gas oil. The core fraction corresponds to an intermediate fraction between the hard fraction and the heavy fraction. The core fraction of the gasoline is rich in mono-olefins and sulfur-containing thiophene-based compounds such as thiophene, methylthiophene and other alkylthiophenes.

In general, the various fractions of gasoline can be obtained by distilling the effluent from the catalytic cracking unit.

A mixture consisting of a hard fraction and a middle fraction of gasoline, or a single intermediate fraction, is treated in a first hydrodesulfurization step HDS1. This step can be carried out in the presence of one or more in-line hydrodesulfurization desulfurization units containing one or more catalysts suitable for performing selective hydrodesulfurization, i. E., Having a degree of mono-olefin hydrogenation of less than 60%, preferably less than 50%, more preferably less than 40% And contacting the gasoline with hydrogen in the reactor.

The operating pressure of the above step is generally in the range of 0.5 MPa to 5 MPa, preferably 1 MPa to 3 MPa. The temperature ranges from 200 캜 to 400 캜, preferably from 220 캜 to 380 캜. When the treatment is carried out in a plurality of series reactors, the average operating temperature of each reactor is higher than the operating temperature of the previous reactor by at least 5 ° C, preferably at least 10 ° C, more preferably at least 15 ° C.

The flow rate ratio between the gasoline being processed is the amount of catalyst used in each reactor, expressed as per m ³ under standard conditions per m ³ catalyst 1 (and also bears a hourly space velocity), 0.5 h ^-1 to 20 h ^-1 range, preferably Is in the range of 1 h ^-1 to 15 h ^-1 . Most preferably, the first reactor is operated at a space-time rate in the range of 2 h ^-1 to 8 h ^-1 .

Hydrogen flow rate of hydrogen flow rate under standard conditions (Nm per hour ³ (normal m ³⁾ (Nm ³ / h) as expressed) and the ratio between the treated supply flow rate (expressed as per m ³⁾ is 50 Nm ³ / m ³ to 1000 Nm ³ / m ³ , preferably 70 Nm ³ / m ³ to 800 Nm ³ / m ³ .

The degree of desulfurization achieved during the HDS1 stage is generally above 80%, preferably above 90%.

After the hydrodesulfurization step, the reaction mixture is cooled to a temperature below < RTI ID = 0.0 > 60 C < / RTI > The gas phase and the liquid phase are separated from the separator. The liquid fraction containing the desulfurized gasoline, and the fraction of dissolved H ₂ S, are transferred to the stripping zone; Mainly composed of hydrogen, and the gaseous fraction containing most of H ₂ S is transferred to the purification region.

The heavy fraction of the gasoline is treated in a separate hydrodesulfurization step HDS2. The step consists of contacting the gasoline with hydrogen in at least one in-line hydrodesulfurization reactor containing at least one catalyst suitable for carrying out hydrodesulfurization. The hydrodesulfurization of the heavy gasoline is preferably carried out in a single step in a single reactor. Hydrodesulfurization can be carried out selectively or non-selectively. In the first case, the degree of hydrogenation of the mono-olefin is less than 90%, preferably less than 80%, more preferably less than 60%.

The operating pressure of the above step is generally in the range of 0.5 MPa to 10 MPa, preferably 1 MPa to 8 MPa. The temperature ranges from 220 캜 to 450 캜, preferably from 250 캜 to 380 캜. When the treatment is carried out in a plurality of series reactors, the average operating temperature in each reactor is higher than the operating temperature of the previous reactor by at least 5 ° C, preferably by at least 10 ° C, more preferably by at least 15 ° C.

The amount of catalyst is the ratio between the flow rate of the gasoline to be treated in use each reactor, expressed as per m ³ under standard conditions per m ³ catalyst 1 (and also bears a hourly space velocity), 0.3 h ^-1 to 20 h ^-1 range, preferably Is in the range of 0.5 h ^-1 to 15 h ^-1 . Most preferably, the first reactor is operated at a space-time rate in the range of from 1 h ^-1 to 8 h ^-1 .

The hydrogen flow rate is in the range of 30 Nm ³ / m ³ to 800 Nm ³ / m ³ (expressed as Nm ³ (Nm ³ / h) per hour of hydrogen flow under normal conditions) and the source flow rate (expressed in m ³ per hour) , Preferably from 50 Nm ³ / m ³ to 500 Nm ³ / m ³ . The ratio is less than 80%, preferably less than 60%, more preferably less than 50%, even more preferably less than 40% of the flow rate ratio used in the desulfurization of the hydrodesulfurization step HDS1.

After the hydrodesulfurization step, the reaction mixture is cooled to a temperature below < RTI ID = 0.0 > 60 C < / RTI > The gas phase and the liquid phase are separated from the separator. The fraction of dissolved H ₂ S, as well as the liquid fraction containing the desulfurized gasoline, is transferred to the stripping zone; Mainly composed of hydrogen, and the gaseous fraction containing most of H ₂ S is transferred to the purification region.

Any catalyst with good selectivity in connection with the hydrodesulfurization reaction can be used in step HDS1 or HDS2. As an example, a catalyst comprising an amorphous porous mineral support selected from the group consisting of alumina, silicon carbide, silica, silica-alumina or titanium or magnesium oxide is used alone or as a mixture with alumina or silica-alumina. Silica, transition alumina group and silica-alumina. Most preferably, the support consists essentially of at least one transition alumina. That is, the support comprises at least 51 wt%, preferably at least 60 wt%, more preferably at least 80 wt%, and even at least 90 wt% of transition alumina. It may optionally be composed of transition alumina alone.

The specific surface area of the support is generally 200 m ² / g or less, preferably 150 m ² / g or less. The catalyst porosity before sulphidation is such that the average pore diameter is greater than 20 nm, preferably greater than 25 nm, or even 30 nm, usually between 20 nm and 140 nm, preferably between 20 nm and 100 nm, 80 nm. The pore diameter is measured by mercury porosimetry at a wetting angle of 140 DEG in accordance with ASTM D4284-92.

The hydrodesulfurization catalyst contains at least one Group V metal and / or at least one Group VIII metal on the support. As the Group V metal, molybdenum or tungsten is common, and as the Group VIII metal, nickel or cobalt is common. According to the invention, the surface density of the Group V metal is such that the oxide of the metal per m ^{2 of} support is in the range of 2 x 10 ^-4 g to 4.0 x 10 ^-3 g, preferably 4 x 10 ^-4 g / m ² To 1.6 x 10 < ^-3 > g / m < ^{2 &} gt ;.

Very preferably, a catalyst or chain catalyst as described in patent application US200600751A1 is used. These catalysts may be used, for example, as catalysts which are not promoted or promoted by refractory oxides, such as alumina, silica, silica-alumina or magnesium, and Group VIII metals, preferably cobalt or nickel, Preferably a molybdenum or tungsten. ≪ Desc / Clms Page number 2 > The catalyst has an average pore diameter of greater than 22 nm. For any chain catalyst, the process comprises a continuous hydrodesulfurization step, wherein the catalytic activity of step n + 1 ranges from 1% to 90% of the catalytic activity of step n.

However, it is possible to use a non-selective catalyst in step HDS2. As an example, a catalyst comprising an amorphous porous mineral support selected from the group consisting of alumina, silicon carbide, silica, silica-alumina or titanium or magnesium oxide is used alone or as a mixture with alumina or silica-alumina. Silica, transition alumina group and silica-alumina. Most preferably, the support consists essentially of at least one transition alumina. That is, the support comprises at least 51 wt%, preferably at least 60 wt%, more preferably at least 80 wt%, or even at least 90 wt% of transition alumina. It may optionally be composed of transition alumina alone. The hydrodesulfurization catalyst contains at least one Group V metal and / or at least one Group VIII metal on the support. As the Group V metal, molybdenum or tungsten is common, and as the Group VIII metal, nickel or cobalt is common. The selectivity or non-selectivity of the hydrodesulfurization catalyst as defined above in the description of the present invention depends on the composition and the manner of preparation of the catalyst. A simple way of changing the selectivity is to change the molar ratio between, for example, the amount of Group VIII and Group VI metals, or optionally the amount of Group VIII and Group VI metals for a given support, And changing the specific surface area.

In a preferred embodiment of the present invention, the excess hydrogen from the hydrodesulfurization steps HDS1 and HDS2 can be combined and processed in a single purification zone. The purified hydrogen is then recycled to the at least one hydrodesulfurization stage HDS1 and HDS2 after a compression stage to compensate for the reduced pressure in the process. To compensate for the hydrogen consumption in the hydrodesulfurization reactor, fresh hydrogen is replenished before or after the compression step.

It may be contemplated to introduce at least one of the hydrodesulfurization steps, preferably at least two of the hydrogens needed for the reaction occurring during the two or more hydrodesulfurization steps via HDS2. Thus, at the end of this stage, the total hydrogen feed required for the steps HDS1 and HDS2 is transferred to only one of the steps, preferably HDS2, and the purge gas from the step is transferred to a purification treatment step, from which the purged gaseous product It is only recycled to the other hydrodesulfurization step. The batch type can minimize the flow rate of recycled hydrogen through the compressor, in which case all of the hydrogen consumed in the two hydrodesulfurization steps is transferred through the HDS2 unit, The purified product is transferred to a purification step where only the HDS1 step is recycled. Since the HDS1 unit requires a lower hydrogen flow rate than the HDS2 unit, a smaller amount of hydrogen is required for recirculation through the compressor, thus reducing the energy consumption of the compressor.

It is possible to devise a process of compounding the vapor fraction from the two stripping columns used in each hydrodesulfurization step (cooling, recycling the condensed liquid to the stripping and purge columns, respectively, and combining with the H ₂ S enriched gas To the purification step).

The fact that the product in the hydrodesulfurization step HDS2 is transported to the diesel pool, the fact that it provides the HDS2 stage, which corresponds to heavy gasoline, means that the gasoline can not be mixed with the intermediate distillate oil in another hydrotreating step, Means increasing the capacity of the treatment step and consequently increasing the capacity in refinery production.

In connection with the present invention, for the following main purposes, it is possible to perform a pre-treatment of the source:

For the purpose of selectively hydrogenating diolefins to mono-olefins,

- Light saturated sulfur-containing compounds, mainly for the purpose of reacting mercaptans with mono-olefins to convert them to heavier sulfides or mercaptans.

Hydrogenation of diolefins to mono-olefins is illustrated below by the conversion of 1,3-pentadiene, which is a labile compound that readily polymerizes to pent-2-ene by hydrogenation. However, the second mono-olefin hydrogenation reaction should be limited because it can form n-pentane as shown in the following examples.

The sulfur-containing compounds to be converted are mainly mercaptans and sulfides. The main mercaptan conversion reaction consists of thioetheration of mono-olefins with mercaptans. The above reaction is exemplified by adding pent-2-ene-propane-2-thiol to form propylpentylsulfide.

In addition, in the presence of hydrogen, hydrogen sulfide can be intermediate formed and added to the unsaturated compound present in the source to modify the sulfur-containing compound. However, this is the path of the lane under the desired reaction conditions.

In addition to mercaptans, compounds which can be modified with heavier compounds include sulfides, predominantly dimethyl sulfide, methyl ethyl sulfide and diethyl sulfide, CS ₂ , COS, thiopane and methyl thiopane.

In any case, it is also possible to confirm the reaction of modifying the hard nitrogen containing compound, mainly nitrile, pyrrole and derivatives thereof, with a heavier compound.

The preprocessing step comprises transferring the source to produce one or more metals of Group VIB (New Group of Periodic Conventions, Handbook of Chemistry and Physics, 76 ^th edition, 1995-1996) and one or more Group VIII non- 9, and 10) on a porous support and contacting the catalyst with a hydrogen stream.

The catalysts of the present invention can be prepared by injecting any technique known to those skilled in the art, particularly the VIII and VIB group elements onto a selected support. The implantation can be performed using manufacturing techniques known to those skilled in the art, such as, for example, dry implantation, in which the element is injected in precise predetermined amounts in the form of a salt soluble in a selected solvent, such as demineralized water To fill the voids of the support as accurately as possible. It is then preferable to dry the support filled with the solution. Preferred supports include alumina, which can be made from any precursor types and molding equipment known to those skilled in the art.

The catalyst, a sulfide form as that obtained after the contact with the degradable sulfur-containing organic compound which can generate hydrogen sulfide (H ₂ S), or at a temperature that is in direct contact with the gas phase H ₂ S flow is diluted in H ₂ It is common to use. This step can be carried out in-situ or off-site (i.e., inside or outside the hydrodesulfurization reactor) at a temperature in the range of 200 ° C to 600 ° C, more preferably in the range of 300 ° C to 500 ° C.

The source is mixed with hydrogen prior to contacting the catalyst. The amount of hydrogen introduced is such that the molar ratio of hydrogen to diolefins to be hydrogenated (stoichiometrically) is in excess of 1 mol / mol and less than 10 mol / mol, preferably 1 mol / mol to 5 mol / mol to be. Too much excess hydrogen may cause excessive mono-olefin hydrogenation, resulting in a decrease in the octane number of the gasoline. The entire source is typically injected into the reactor inlet. In any case, however, it may be advantageous to inject a fraction or all of said source between two successive catalyst beds of the reactor. With this operation, the reactor can continue to operate if the inlet to the reactor is blocked by the deposition of polymer, particles or gum in the source.

The mixture consisting of gasoline and hydrogen has a liquid hourly space velocity (LHSV) in the range of from 1 h ^-1 to 10 h ^-1 at a temperature in the range of from 80 ° C to 220 ° C, preferably from 90 ° C to 200 ° C, 1 < / RTI > (l / lh). The pressure is controlled such that the reaction mixture is predominantly liquid in the reactor. The pressure ranges from 0.5 Mpa to 5 Mpa, preferably from 1 Mpa to 4 Mpa.

The content of diolefins and mercaptans in gasoline treated under the above-mentioned conditions is reduced. Generated gasoline generally contains less than 1% by weight, preferably less than 0.5% by weight, of diolefins. The normally converted amount of a hard sulfur-containing compound having a boiling point lower than the boiling point of thiophene (84 占 폚) is more than 50%. It is therefore possible to separate the hard fraction of the gasoline by distillation and to transfer the fraction directly to the gasoline pool without further treatment.

Preferred embodiments of the method of the present invention are shown in Figs. 1, 2 and 3. Fig.

Description of Figure 1:

The core gasoline, gasoline A, delivered to line 1 was mixed with hydrogen entering from recycle compressor P1 through line 20. The thus formed mixture is injected into the reaction region R1. The effluent transported through the line 4 is cooled in the exchanger zone E1 and condensed with hydrocarbons and then the mixture is injected via line 6 into the separation zone S1. The separation zone S1 produces a gaseous fraction consisting essentially of hydrogen, H ₂ S and light hydrocarbons and extracted through line 8 and a liquid fraction extracted through line 9. Thereafter, the liquid fraction is injected into the stabilization zone C2, where H ₂ S dissolved in the hydrocarbon is extracted via the upper line 15. Gasoline recovered through line 16 from the bottom of column C2 may be directly delivered to the gasoline pool.

Heavy gasoline, gasoline (B), which is transported to line (3), is mixed with fresh hydrogen supplied via line (2). The thus constituted mixture is injected into the reaction zone R2. The effluent transferred via line 5 is cooled in the exchanger zone E2 and condensed with hydrocarbons and then the mixture is injected into the separation zone S2 via line 7. The separation zone S2 produces a gaseous fraction consisting essentially of hydrogen, H ₂ S and light hydrocarbons and extracted through line 10 and a liquid fraction extracted through line 11. The liquid fraction is then injected into the stabilization zone C3 where H ₂ S dissolved in the hydrocarbon is extracted via the top line 17. The heavy desulfurized gasoline recovered via line 18 can be transferred to gasoline pools or to intermediate distillate pools.

The stabilization zones (C2) and (C3) each comprise a distillation column. In order to limit operating costs and investment costs, it is advantageous to blend the two column distillates prior to cooling and condensing and transfer them to a reflux drum together. The two columns can then be operated with a common reflux region.

The hydrogen introduced from the separators S1 and S2 through the lines 8 and 10 respectively is introduced into the purification zone C1 before being treated in the general purification zone C1 which consists of washing with an aqueous amine solution using known techniques Mixed. After purification, the H ₂ S-free hydrogen which is conveyed to line 13 and compressed in recycle compressor P 1 is then mixed with gasoline A via line 20.

In a further embodiment of the invention, the supplemental hydrogen is injected through the line 12 upstream of the purification zone Cl. Thereafter, the hydrogen required to treat gasoline (B) is injected via line (19) into the hydrodesulfurization step of reaction zone (R2).

Description of Figure 2:

The numbers used in the figure correspond to the numbers used in FIG.

Figure 2 shows a further variant of the invention. In this modification, the hydrogen fraction flowing from the separation region S1 through the line 8 is injected into the reaction region R2 through the line 21 without purification treatment.

Description of Figure 3:

FIG. 3 illustrates a chain pretreatment step consisting predominantly of hydrogenating the diolefin, modifying the hard sulfur containing compound to a heavier compound, and a selective hydrodesulfurization step.

The pretreatment step R3 can be carried out on the total gasoline injected via line 1 or on the gasoline recovered via line 3 from above the distillation column C4. In the latter case, gasoline (A) is transported directly to column (C4) without pretreatment.

When all gasoline is pretreated, hydrogen is injected via line 10, a selective hydrogenation step, and a pre-treatment step (R3) corresponding to the step of modifying the light saturated sulfur-containing compound to a heavier compound . The resulting gasoline is then passed through a line 4, which is a mixture of core gasoline and light gasoline as described in the present invention and two oils in column C4, heavy oil extracted via line 4, corresponding to the heavy gasoline described in the present invention, To the lighter fractions recovered via line 3, corresponding to the distillation fraction. The hard fraction can then be distilled in the second column (C5) to separate the core gasoline discharged through line (6) from light gasoline discharged through line (7). The light gasoline recovered through line 7 is typically sulfur-depleted and can be transported directly to the gasoline pool without further treatment.

The core and heavy gasoline recovered respectively through lines 6 and 4 are treated in one or more hydrodesulfurized zones according to the present invention and treated with gasoline H through line 8 and gasoline (J), which are respectively transported to the gasoline pool and the middle distillate pool.

It may be advantageous to generate the three gasoline fractions described above in a single column equipped with side stream discharge passages in which the core gasoline is extracted. In a further implementation of the invention, the column for distilling all the gasoline injected through line 1 may be a single column with an inner wall.

When the pre-treatment step R3 is applied to the incoming gasoline from the line 3, hydrogen is injected through the line 11. [ By doing this, only the gasoline fraction corresponding to the fraction depleted in heavy gasoline in the pretreatment step (R3) is transferred to the catalyst, such as arsenic or silicon, which is generally concentrated in the heavy gasoline fraction, And has the advantage of reducing potential pollutants.

Example

Source  Produce

Gasoline (a), whose boiling point ranged from 6 ° C to 236 ° C and was derived from the catalytic cracking unit, was distilled in a batch distillation column to produce the following four fractions:

(A1) corresponding to a fraction of 6 to 118 캜;

Oil (a2) corresponding to the 188 캜 to 236 캜 fraction;

Oil (a3) corresponding to a fraction of 6 to 209 占 폚;

Oil (a4) corresponding to a fraction of 209 캜 to 236 캜.

The properties of the various fractions are shown in Table 1.

Characteristics of distillation oil a a1 a2 a3 a4 100% 85% 15% 92% 8% S Ppm by weight 390 253 1173 250 1875 BrN g / 100g 41 46.5 11 43 6 RON 91.7 91.5 94.5 92.1 94.3 MON 80 81.3 82.8 81.9 82.9 Fraction ℃ 6-236 6-188 188-235 6-209 209-235
- ppm by weight is the weight of one-half million sulfur measured using the ASTM D-5453 method;
- BrN is the bromine number measured using the ASTM D-1159 method.

Example 1 (Comparative Example)

A 100 ml volume of catalyst HR806S (a sulfur-containing catalyst based on cobalt and molybdenum), marketed by Axens, was charged into a pilot unit reactor. The catalyst had pre-sulphiding and pre-activating functions outside the system. Thus, no additional sulfiding step was necessary.

Gasoline (a) was mixed with hydrogen prior to injection into the reactor. The gasoline flow rate was 400 ml / h and the hydrogen flow rate was 116 Nl (normal liters) per hour. The hydrogen flow rate was such that the H ₂ / HC ratio was 290 Nl / l as hydrogen Nl per liter of the source. The temperature was adjusted to 260 캜 and the pressure was 2 MPa. Cool the resulting gasoline (c1), to remove the H ₂ S dissolved in the stripped hydrogen stream.

After analysis, the gasoline contained 38 ppm of sulfur, including 14.0 ppm of the mercaptan form. Its research octane number (RON) was 90.60 and its motor octane number (MON) was 79.40.

Example 2 ( Example of the present invention)

340 ml / h of gasoline (a1) was mixed with 98 Nl / h of hydrogen and injected into 85 ml volume of catalyst HR806S. The hydrogen flow rate was such that the H ₂ / HC ratio was 300 Nl / l as hydrogen Nl per liter of the source. The reactor temperature was adjusted to 260 ° C and the pressure was adjusted to 2 MPa. The resulting gasoline (b1) contained 19 ppm of sulfur, including 8 ppm of the mercaptan type.

60 ml / h of gasoline (a2) was mixed with 14.4 Nl / h of hydrogen and injected into a 15 ml volume of catalyst HR806S. The hydrogen flow rate was such that the H ₂ / HC ratio was 240 Nl / l as hydrogen Nl per liter of the source. The reactor temperature was adjusted to 260 ° C and the pressure was adjusted to 2 MPa. The resulting gasoline (b2) contained 90 ppm of sulfur, including 4 ppm of the mercaptan type.

All in all, in order to process the fractions (a1) and (a2), hydrogen flow rate, as the hydrogen supply source 1 Nl per l, was the flow rate of the H ₂ / HC ratio to be 290 Nl / l.

Gasolines (b1) and (b2) were mixed in an amount of 85% by weight of gasoline (b1) and 15% by weight of gasoline (b2). The thus prepared mixture (c2) was analyzed. It contained 30 ppm of sulfur, including 8.0 ppm of mercaptans. Its research octane number (RON) was 90.80 and its motor octane number (MON) was 79.50. Fraction (b2) could also be transferred to a middle distillate pool with a very low sulfur content.

By comparing the gasolines (c1) and (c2) produced in Examples 1 and 2, treating the gasoline separated in two separate oil fractions while maintaining the same overall hydrogen flow rate increases the octane number of the desulfurized gasoline, Especially the amount of mercaptans, can be significantly reduced.

Example 3 ( Example of the present invention)

Gasoline (b1) was obtained using the preparation process described in Example 2. < Desc /

60 ml / h of gasoline (a2) was mixed with 6.3 Nl / h of hydrogen and injected into a 15 ml volume of catalyst HR806S. Hydrogen flow rate, as the hydrogen supply source 1 Nl per l, was the flow rate of the H ₂ / HC ratio to be 105 Nl / l. The reactor temperature was adjusted to 260 ° C and the pressure was adjusted to 2 MPa. The resulting gasoline (b5) contained 135 ppm of sulfur, including 6 ppm of the mercaptan type.

Gasolines (b1) and (b5) were mixed in an amount of 85% by weight of gasoline (b1) and 15% by weight of gasoline (b5). The thus-prepared mixture (c4) was analyzed. It contained 36 ppm of sulfur, including 8.0 ppm in the form of mercaptans. Its research octane number (RON) was 90.90 and its motor octane number (MON) was 79.60. Fraction (b5) could also be transferred to a middle distillate pool with a very low sulfur content.

All in all, in order to process the fractions (a1) and (a2), hydrogen flow rate, as the hydrogen supply source 1 Nl per l, was the flow rate of the H ₂ / HC ratio to be 270 Nl / l.

Example 4 ( Example of the present invention)

368 ml / h of gasoline (a3) was mixed with 108.2 Nl / h of hydrogen and injected into a 92 ml volume of catalyst HR806S. The hydrogen flow rate was such that the H ₂ / HC ratio was 294 Nl / l as hydrogen Nl per liter of the source. The reactor temperature was adjusted to 260 ° C. The resulting gasoline (b3) contained 20 ppm of sulfur, including 7 ppm of the mercaptan type.

32 ml / h of gasoline (a4) was mixed with 7.5 Nl / h of hydrogen and injected into an 8 ml volume of catalyst HR806S. The hydrogen flow rate was such that the H ₂ / HC ratio was 234 Nl / l as hydrogen Nl per liter of the source.

The reactor temperature was adjusted to 260 ° C. The resulting gasoline (b4) contained 140 ppm of sulfur, including 3 ppm of the mercaptan type.

Gasolines (b3) and (b4) were mixed in an amount of 92% by weight of gasoline (b3) and 8% by weight of gasoline (b4). The thus prepared mixture (c3) was analyzed. It contained 30 ppm of sulfur, including 7.0 ppm of mercaptans. Its research octane number (RON) was 91.00 and its motor octane number (MON) was 79.70. Fraction (b4) could also be transferred to a middle distillate pool with a very low sulfur content.

All in all, in order to process the oil (a3) and (a4), hydrogen flow rate, as the hydrogen supply source 1 Nl per l, was the flow rate of the H ₂ / HC ratio to be 290 Nl / l.

By comparing Examples 2 and 4, it was evident that by separating a heavy fraction having a boiling point greater than 209 ° C from gasoline and treating it in an independent hydrodesulfurization zone, the octane number of the desulfurized gasoline could be increased and the amount of mercaptan could be reduced .

Example 5 (Comparative Example)

340 ml / h of gasoline (a1) was mixed with 98.6 Nl / h of hydrogen and injected into 85 ml volume of catalyst HR806S. The hydrogen flow rate was such that the H ₂ / HC ratio was 290 Nl / l as hydrogen Nl per liter of the source. The reactor temperature was adjusted to 260 ° C and the pressure was adjusted to 2 MPa. The resulting gasoline (b6) contained 22 ppm of sulfur, including 9 ppm of the mercaptan type.

60 ml / h of gasoline (a2) was mixed with 17.4 Nl / h of hydrogen and injected into a 15 ml volume of catalyst HR806S. The hydrogen flow rate was such that the H ₂ / HC ratio was 290 Nl / l as hydrogen Nl per liter of the source. The reactor temperature was adjusted to 260 ° C and the pressure was adjusted to 2 MPa. The resulting gasoline (b7) contained 80 ppm of sulfur, including 4 ppm of the mercaptan type.

All in all, in order to process the fractions (a1) and (a2), hydrogen flow rate, as the hydrogen supply source 1 Nl per l, was the flow rate of the H ₂ / HC ratio to be 290 Nl / l.

Gasolines (b6) and (b7) were mixed in an amount of 85% by weight of gasoline (b6) and 15% by weight of gasoline (b7). The mixture (c5) thus constituted was analyzed. It contained 31 ppm sulfur, including 8.3 ppm mercaptans. Its research octane number (RON) was 90.65 and its motor octane number (MON) was 79.40.

Example One
Comparative Example 2
The
Example 3
The
Example 4
The
Example 5
Comparative Example Cut point (℃) radish 188 188 209 188 H ₂ / HC (HDS ₂ ) for H ₂ / HC (HDS 1),% radish 80 35 80 100 Sulfur content (ppm) 38 30 36 30 31 Amount of mercaptan (ppm) 14.0 8.0 8.0 7.0 8.3 RON 90.60 90.80 90.90 91.00 90.65 MON 79.40 79.50 79.60 79.70 79.40
H ₂ / HC (HDS ₂ ) to H ₂ / HC (HDS 1),%: Hydrodesulfurization step The hydrogen flow rate (expressed in Nm ³ per hour) as a percentage of the flow rate used for desulfurization in HDS ¹ and the source Flow rate (expressed in m ³ per hour)

By comparing Examples 1, 2, 4, and 5, it is possible to increase the octane number of the desulfurized gasoline by increasing the amount of sulfur and mercaptan, in particular by treating the gasoline separated in two separate oil fractions in parallel while maintaining the same overall hydrogen flow rate It can be remarkably reduced.

Further, the ratio of the hydrogen flow rate in the hydrodesulfurization step HDS2 to the hydrogen flow rate (expressed in Nm ³ per hour) under standard conditions and the source flow rate (expressed in m ³ per hour) to be treated corresponds to the desulfurization in the hydrodesulfurization step HDS 1 It is contemplated to increase the RON and MON octane values by significantly reducing the amount of sulfur and mercaptans at a flow rate that is less than 80% of the flow rate used in Examples 2 and 4.

According to the present invention, it is possible to economically solve the triple problem of reducing the sulfur content in the fuel, limiting the mercaptan content in the low-sulfur gasoline, and verifying the fuel production direction with gasoline oil or middle distillate according to the market demand have. The method described in the present invention can be used to limit energy consumption due to the required compression of hydrogen recycled to the hydrodesulfurization step.

Claims (11)

A process for the production of gasoline having a low sulfur and mercaptan content, comprising two or more hydrodesulfurization steps HDS1 and HDS2 operated in parallel for two individual gasoline fractions constituting the source, said source having the following three fractions: A hard fraction corresponding to a gasoline fraction having a boiling point of less than 100 占 폚, - a heavy gasoline fraction corresponding to a gasoline fraction having a boiling point greater than 180 ° C, - a core fraction corresponding to an intermediate fraction between said light and heavy fractions , Wherein the hydrogen flow rate at the hydrodesulfurization step HDS2 is equal to the hydrogen flow rate (expressed in Nm ³ (normal m ³ ) per hour) under standard conditions, and the gas stream from the catalytic cracking unit The flow rate is such that the ratio between the source flow rate (expressed in m ³ per hour) is less than 80% of the flow rate used for desulfurization in the hydrodesulfurization stage HDS 1, The mixture consisting of a hard gasoline fraction and an intermediate fraction, or a single intermediate fraction, is treated in a hydrodesulfurization step HDS1 and the treatment is carried out in the presence of one or more catalysts suitable for carrying out selective hydrodesulfurization to a degree of mono-olefin hydrogenation of less than 60% Wherein the heavier fraction of gasoline is treated in a hydrodesulfurization step HDS2 and wherein the treatment is carried out in the presence of one or more catalysts suitable for carrying out hydrodesulfurization Comprising contacting the gasoline with hydrogen in at least one in-line hydrodesulfurization reactor, wherein the hydrodesulfurization is carried out selectively or non-selectively, and the degree of hydrogenation of the mono-olefin is 90% . ≪ / RTI > The process according to claim 1, comprising a single zone for refining and recycling excess hydrogen from the hydrodesulfurization stages HDS1 and HDS2. 3. The process according to claim 1 or 2, wherein all of the hydrogen required for the reactions occurring during the two hydrodesulfurization steps is introduced via only one of the hydrodesulfurization stages HDS1 and HDS2, Wherein the purified gaseous product is recycled only to the other hydrodesulfurization unit. 4. The process according to claim 3, wherein all of the hydrogen required for the reactions occurring in the two hydrodesulfurization steps is introduced via the hydrodesulfurization step HDS2. According to claim 1 or 2, wherein the hydrogen flow rate in the hydrodesulfurization unit HDS1 is the ratio between the hydrogen flow rate (expressed as per m ³⁾ supply flow rate to be processed and (in terms of per Nm ³⁾ under standard conditions 50 Nm ³ / m ³ to 1000 Nm ³ / m and the flow rate so that the ^third range, hydrodesulfurization units hydrogen flow rate in the HDS2 a hydrogen flow rate under standard conditions (in terms of per m ³⁾ supply flow rate to be processed and (in terms of per Nm ³⁾ between And the ratio is in the range of 30 Nm ³ / m ³ to 800 Nm ³ / m ³ . delete 3. The method according to claim 1 or 2, Di-olefins are selectively hydrogenated with mono-olefins, The pre-treatment is carried out to react the light-saturated sulfur-containing compound with the mono-olefin to convert to the heavier sulfide or mercaptan. The catalyst according to claim 1 or 2, wherein the catalyst used in the hydrodesulfurization step HDS1 and HDS2 comprises a support, a catalyst comprising a Group VI metal promoted or not catalyzed by a Group VIII metal and having an average pore diameter greater than 22 nm, Chain catalyst. The catalyst according to claim 1 or 2, wherein the catalyst used in the hydrodesulfurization step HDS1 and HDS2 comprises an amorphous porous mineral support, one or more Group VI metals, or one or more Group VIII metals, or one or more Group VI metals and Group VIII metals , and the porosity of the sulfide prior to the catalyst including the average pore diameter of 20 nm, porosity and specific surface area of the support was 1 m ⅵ group metal of the metal oxide per ^{2 2} x 10 ^-4 g to 4.0 x 10 so that ^{excess- 3} < / RTI > g. The process according to claim 8, wherein the Group V metal is molybdenum or tungsten and the Group VIII metal is nickel or cobalt. The process according to claim 9, wherein the Group V metal is molybdenum or tungsten and the Group VIII metal is nickel or cobalt.

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